package com.hit.basmath.learn.linked_list;

import com.hit.common.ListNode;

/**
 * 2. Add Two Numbers
 * <p>
 * You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.
 * <p>
 * You may assume the two numbers do not contain any leading zero, except the number 0 itself.
 * <p>
 * Example:
 * <p>
 * Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
 * Output: 7 -> 0 -> 8
 * <p>
 * Explanation: 342 + 465 = 807.
 */
public class _2 {
    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {
        ListNode dummyHead = new ListNode(0);
        ListNode p = l1, q = l2, curr = dummyHead;
        int carry = 0;
        while (p != null || q != null) {
            int x = (p != null) ? p.val : 0;
            int y = (q != null) ? q.val : 0;
            int sum = carry + x + y;

            carry = sum / 10;
            curr.next = new ListNode(sum % 10);
            curr = curr.next;

            if (p != null) {
                p = p.next;
            }
            if (q != null) {
                q = q.next;
            }
        }

        if (carry > 0) {
            curr.next = new ListNode(carry);
        }

        return dummyHead.next;
    }
}
